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    <meta charset="UTF-8">
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    <title>Document</title>
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<body>
    <script>
        function person(firstName, lastName) {
            this.firstName = firstName;
            this.lastName = lastName;
        }
        const lydia = new person("lydia", "mallie");
        const sarash = person("sarash", "smith");
        console.log(lydia);//person {firstName: "lydia", lastName: "mallie"}
        console.log(sarash);//undefined
        console.log(111);
    </script>
</body>

</html>